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Our AI overlords did a pretty good job of implementing this on the minischeme interpreter I like to poke at from time to time. Though, apparently, a SECD machi

Our AI overlords did a pretty good job of implementing this on the minischeme interpreter I like to poke at from time to time. Though, apparently, a SECD machine isn't as amenable to this as I originally thought. My intuition was you just pass the different SECDs as arguments between the action routines and let the compiler do it's magic but they were like "oh no, silly human, it doesn't work like that." It turns out doing it their way allowed scheme's mandatory tail-call optimization (TCO) to naturally fall out of the implementation which I thought was kind of special. Kudos, robots... Haven't looked at how python does its thing in quite a long time but I believe it doesn't have TCO so maybe this is a step in that direction?

rurban 2y ago
It's unrelated to a python TCO. It's only about new optimizations now possible with the new clang 15 musttail attribute in the inner VM loop. while op { switch op case bla: ...} to reduce register pressure in the ops. This is possible for all other dynamic language VM's also (which didn't resort to luajit's assembly vm loop). Compilers register allocation can never better when they cannot prove TCO. With this they can skip that